U.S. Central Command said Friday that airstrikes in Iraq and Syria in the fight against the Islamic State led to the deaths of 20 civilians and about a dozen injuries on the ground in recent months.

The statistics were released after the command conducted several civilian casualty assessments. It is believed that the civilians died as a result of nine separate airstrikes between Sept. 10, 2015 and Feb. 2, 2016. All were determined to have been the unintended result of attacks on legitimate targets.

“There are going to be civilian casualties,” Col. Patrick Ryder, a spokesman from the U.S. Central Command, said. “There are risks associated with these strikes.”

Six of the strikes were in Iraq and three were in Syria. Armed drones were involved in some cases; manned aircraft in others.

The U.S. has spent about $7 billion in the fight against ISIS, which amounts to about $11.6 million for the 602 days of operations.

Since the start of U.S. airstrikes in 2014, the U.S. has acknowledged a total of 41 civilian deaths in Iraq and Syria, including those announced Friday.

The most deadly of the nine investigated airstrikes, in terms of civilian casualties, was an Oct. 5, 2015 attack on an ISIS mortar position in Atshanah, Iraq. Central Command said eight civilians were killed; it did not elaborate on the circumstances.

On Dec. 12, 2015, a strike on a suspected ISIS checkpoint in Ramadi killed five civilians. Central Command said they "unexpectedly moved into the target locations after weapons were already in flight.”

In the 6-month period between September and February, "the U.S. conducted 2563 airstrikes. We take all reasonable measures during the planning and execution of airstrikes in an effort to mitigate risks to non-combatants, and to comply with the Law of Armed Conflict," CENTCOM Cpt. Michael Meyer said.

Fox News' Lucas Tomlinson and The Associated Press contributed to this report.